The statements in this section merely provide background information related to the present disclosure and may not constitute the prior art.
There are active researches and developments of methods for using ultrasound to check the internal status of materials, or applying it to diagnosis and treatment toward human health as medical field and some other industrial areas have already commercialized the applied ultrasonic technologies.
An exemplary application of ultrasound in medical field is diagnosis such as prenatal diagnosis or cancerous tissue diagnostics, and therapies such as fat removal or destruction of cancerous tissue (or malignant tumors).
A method is recently known for acquiring images of elastic deformations inside the viscoelastic medium by giving a strong impact of focused ultrasonic waves to a point of the viscoelastic medium and thus using transverse elastic waves generated from the focal point as being the wave source. One of the related techniques is suggested by Korean Patent Registration No. 10-0782045 invented by Kim; Cheol An, et al., assigned to Medison Co., Ltd., and entitled ultrasonic diagnostic system for providing elastic image with additional information.
If two substances with different moduli of elasticity are subject to transverse elastic waves generated, the substances experience different elastic deformations. For example, since such tissue of the body as cancer or tumor is more solid than normal surrounding tissue, the former deforms less than the latter by the transverse elastic waves. This enables the chronological sequence of images to be acquired and visualized corresponding to elastic deformations of tissues by propagations of the transverse elastic wave from the focusing of ultrasonic waves and thereby observing and diagnosing the internal state of the tissues.
In general, since a small impact of the focused ultrasonic waves at a point (hereinafter called ‘focal point’) causes a minute elastic deformation, an adequately accurate diagnosis of a tissue needs the viscoelastic medium to have greater elastic deformations by generating stronger transverse elastic waves from focusing high-intensity ultrasonic waves to more accurately diagnose the viscoelastic medium tissue.
However, when applying such use of transverse elastic waves to body tissue, the heat generated at the focus areas by the ultrasonic waves may cause destruction of the normal tissue and excessive deformations of the focus areas to give rise to an incoherence within the tissue, which undesirably puts the body under too much strain of the high-intensity focused ultrasonic signals for longer than a proper period of time (exposure time).
On the other hand, International Publication No. WO2007/110375 invented by Jérémy Bercoff, David Sabery, et al. and coapplied by Super Sonic Imagine (Titled A Method and A Device for Imaging A Visco-elastic Medium) suggests a technology to focus ultrasonic waves on a number of locations, simultaneously or in alternation.